The present invention relates to a process for uniformly blending a hydraulic cement or similar powder binding agent with a liquid stabilizing agent and to moulded configurations prepared with the blend. The moulded configurations are found to be highly stable against deterioration which normally affects hydraulic cement or similar powder binding agents.
Hydraulic cement of the general type which serves as binding agents for particulate materials in concrete or the like, may be prepared by burning either an argillaceous limestone, or a limestone interground with special portions of clay or shale. After being kiln processed prepared, the powdered cement must be used while fresh or otherwise special conditioning must be assured to avoid the art recognized disadvantage of limited tenability.
Even within periods of time such as three months, cement tends to deteriorate such that when it is used as a binding agent in concrete, an inferior product is found to result. This tendency to deteriorate renders powdered cement unsuitable for transportation either in bags or bulk over long distances or for extended periods of time.
In addition to the expense of packaging cement in bags, there is also the problem of breakage when bags are stacked in high layers, coupled with the problems of transport and breakage in handling of the bags.
It appears that one factor which causes cement to deteriorate is atmospheric carbon dioxide which tends to react with silicate and aluminate components of the cement, and form products which render the cement useless in preparation of durable concrete.
Another factor which causes cement to deteriorate is atmospheric moisture which tends to prematurely set the cement.
One attempted solution to preserve cement has been to store the cement in specially conditioned rooms.
These specially conditioned rooms are expensive to maintain and are of limited effectiveness due to the fact that the powdered cement contains a high percentage of intermixed air with the cement which results during bagging.
Another attempted solution to preserve cement has been by moulding powdered cement with from about 2 to 5% by weight of water. However, when the moulds are pulverized, it is found that very fine cement particles such as 1 to 5 mm diameter become water reacted and bind together prematurely. Thus, this reacted particles no longer usefully serve in the preparation of concrete.
It is found that after pulverization of these water conditioned cements, the resultant powders have decreased strength properties when processed into concrete as opposed to the original starting material. An analysis of the pulverized cement to its original fineness shows that by using water as a binding agent during compressing, the loss of ignition will raise from above the 5%, a level which has been considered in the art to be unacceptable. Typically, in the cement processing art, the maximum figure for loss of ignition is fixed between 3 to 5%.
It has now been found however, that by practice of the present invention, the difficulties and disadvantages of prior art attempts to stabilize cement from deterioration have been overcome in a simple, highly efficient manner.